Personally I don't like dynojet as much as the other options out there. They read notorously high for hp, fine for comparison purposes, but really just an ego boost for said owner. Also the base model (which many companies buy) doesn't have any kind of load control, which honestly is the only way to tune with a dyno. Doing pulls through the rev range and getting your AFR is nice and all, but it's not a very useful tuning aid, you might as well just buy a wideband with datalogger. (not to say these aren't useful, I just wouldn't want to spend a minimum of $25k US for a dynojet and not be able to tune accurately) If the purchaser springs for the extra's with the dynojet (load control, wideband, etc) it brings it up to the level of most of the other dyno's on the market.
For me, I want to be able to tune. I don't care about HP numbers. Which is why I am trying to buy a dyno dynamics setup for my shop. I can hold RPM and LOAD anywhere I want. I can simulate going up a hill at 4000rpm in 4th gear, then at 4250rpm, then at 4500rpm, and hold it there while I do my tuning for that specific cell. I can hold it there and play with my timing to see how much power I gain or lose at that specific rpm, in real time. It might cost twice as much as a dynojet, but I think the results will be well worth it in my customers eyes. And if all they care about is hp numbers, then we can do that too.
However, as long as you use the same dyno back to back, and if you are comparing mods done to your car to see the results, any dyno will help you there.